Chapter 2: Processing Flashcards
What is the most common dehydrating agent?
Alcohol.
During microtomy, it is noted that many of the tissues are very hard and shrunken. What happened?
The infiltrating paraffin was too hot.
What is the appropriate temperature range for infiltrating paraffin during processing?
No more than 2-4C above the melting point of paraffin.
Decalcification of small specimens can be achieved by fixation in:
Zenker. Because it contains acetic acid, it would be ideal for bone marrows and small needle cores.
What is a major disadvantage of aliphatic clearing agents?
They are incompatible with mounting media.
What is an aliphatic clearing agent?
A xylene substitute.
What will cause sensitization with prolonged use?
Limonene. It can also cause allergic reactions in some individuals.
Too speed up the lab’s processing of all surgical tissue, the temperature of all fixation, dehydrating and clearing steps has been set to 45C. What will this result in?
Microchatter due to the removal of bound water from the tissue.
What does limonene function as?
Limonene is a xylene substitute so it would be a clearing agent.
What is one advantage of aliphatic hydrocarbons?
They are low in toxicity and sensitization (sensitivity).
What is one disadvantage of using heat at all stations in the tissue processor?
Some tissues will become hard.
Dehydration refers to the removal of:
Water.
What kind of decalcification process may cause damage to the tissue?
Electrolytic.
Is chloroform combustible?
No, but it is very toxic.
What groups of reagents are used for dehydration?
Dioxane, methanol and ethanol.
When is EDTA NOT a suitable choice when decalcifying bonemarrow specimens?
When a diagnosis is required within 48 hours.
A clearing agent MUST be miscible with:
Dehydrants and infiltrating media (the steps before and after it).
Why should the alcohols be changed routinely on the tissue processor?
The alcohols absorb water from the tissues and become diluted over time.
After decalcification, what should you do with the tissue?
It should be washed in water to halt the reaction.
What is a common chelating agent used for decalcification?
EDTA.
How does ethanol function during processing?
It functions as a dehydrant.
Butyl alcohol is used as a dehydrant for what kind of tissue?
Plant tissue.
The processing step that assures that alcohol is removed from the tissue is the:
Clearing step.
Dehydrating tissue in graded alcohols instead of only absolute is superior because:
Tissue shrinkage is minimized when graded alcohols are used.